This invention relates in general to laser imaging systems and more particularly to a contaminant removal system in a thermal processor of a photothermographic laser imaging system.
Laser imaging systems are widely used in commercial, industrial, and medical imaging fields. In the medical imaging field, photothermographic laser imaging systems are used to reproduce digital medical images in heat processable photothermographic film. After the film is exposed to a digital medical image, the film is processed by a thermal processor to produce a visual representation of the medical image on the film. The thermal processor includes a rotatable heated drum having circumferentially arrayed pressure rollers to hold the film in contact with the heated drum during development. After development, the film is cooled and output to a user.
During the heat development process of the exposed photothermographic media, air-borne contaminants are produced that can produce image artifacts in the developed film image. Airflow in the exit region from the drum has resulted in image artifacts that have a Christmas tree type of profile or wispy appearance.
There is thus a need for improving air contaminant removal in heated drum thermal processors in order to minimize image artifacts in developed film.
According to the present invention, there is provided a solution to these problems.
According to an aspect of the present invention there is provided, a thermal processor having a contaminant removal system comprising: a heated drum for heat developing exposed heat developable media which emit air-borne contaminants during said development; a plurality of rollers located about a circumferential segment of said drum to hold an exposed media in contact with said drum; an enclosure for enclosing said heated drum and plurality of rollers, said enclosure including a first upper curved member spaced from and enclosing said rollers and the upper portion of said drum and a second lower curved member spaced from and enclosing said lower portion of said drum, said first and second curved members having first ends spaced from each other and defining a film entrance region, and further having second ends spaced from each other and defining a film exit region; wherein said first upper curved member includes a curved duct having a first opening above said rollers and a second opening configured to direct gaseous fluids away from the film exit from said drum; a top condensation trap communicating with said second opening of said duct; a bottom condensation trap; and an air flow control system for drawing ambient air from outside said enclosure through said film entrance region, splitting said air flow into (a) a top flow stream which passes between said first member over said rollers, through said duct and through said top condensation trap where air-borne contaminants are condensed and said air stream is cooled, and (b) a bottom flow stream which passes between said second member and said lower portion of said drum and through said bottom condensation trap where air-borne contaminants are condensed and said bottom flow stream is cooled.
The invention has the following advantages.
1. Air contaminants produced during development of heat processable exposed media in a heated drum thermal processor are removed in an efficient and cost effective manner.
2. Image artifacts are minimized in heat developed exposed media.
3. Air temperature is minimized at the filter inlet thus increasing filter life and effectiveness.